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            <li class="nav-item" data-level="1"><a href="#_1" class="nav-link">硬盘结构</a>
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<h1 id="_1">硬盘结构</h1>
<p><img alt="img" src="../images/hard_disk%20_structure.png" />  </p>
<h3 id="platter">盘片（platter）</h3>
<p>硬盘一般有多个盘片，每个盘片可以有两个面(Side)，第 1 个盘片的正面称为 0 面，反面称为 1 面；第 2 个盘片的正面称为 2 面，反面称为 3 面...</p>
<h3 id="head">磁头（head）</h3>
<p>每个盘面对应一个磁头(head)用于读写数据。第一个盘面的正面的磁头称为 0 磁头，背面称为 1 磁头；第二个盘片正面的磁头称为 2 磁头，背面称为 3 磁头...因此，盘面数和磁头数是相等的。</p>
<h3 id="track">磁道（track）</h3>
<p>每个盘片的每个盘面被划分成多个狭窄的同心圆环，我们将这样的圆环称为磁道(Track)，每个盘面可以划分多个磁道。每个盘面的最外圈，离盘心最远的地方是 0 磁道，向盘心方向依次增长为 1 磁道，2 磁道，3 磁道...</p>
<h3 id="sector">扇区（sector）</h3>
<p>把每个磁道划分成若干弧段，每段称为一个扇区(Sector),扇区是硬盘上存储的物理单位，扇区的编号是从 1 开始，而不是 0，物理扇区是连续的，但逻辑扇区不一定是连续的。  <br />
<img alt="img" src="../images/cross_factor.jpg" /></p>
<h5 id="_2">交叉因子</h5>
<p>交叉因子是指低级格式化硬盘时必须设定扇区“间隔因子”值，间隔因子通俗的讲，是指低级格式化后，任意一个扇区和它下一个扇区相隔多少个物理扇区块。间隔因子为 1 时，扇区是连续的。间隔因子与硬盘转速、CPU速度、主板相匹配，否则影响硬盘性能。</p>
<h3 id="cylinder">柱面（cylinder）</h3>
<p>不同面上相同编号的磁道组成了一个圆柱面，即所称的柱面(Cylinder)，磁盘的柱面数量与一个盘面上的磁道数量是相等的。    </p>
<h1 id="_3">硬盘接口</h1>
<p><img alt="img" src="../images/ide_sata.jpg" />
<img alt="img" src="../images/ide_sata2.jpg" />
<img alt="img" src="../images/scsi.jpg" />
<img alt="img" src="../images/scsi_line.jpg" />
<img alt="img" src="../images/sas_sata.jpeg" />
<img alt="img" src="../images/sas2.png" />
<img alt="img" src="../images/sas_line.png" />
<img alt="img" src="../images/m_2.jpg" />    </p>
<p>IDE（Integrated Drive Electronics）也叫 PATA（Parallel Advanced Technology Attachment）   </p>
<table>
<thead>
<tr>
<th>标准</th>
<th>速度</th>
</tr>
</thead>
<tbody>
<tr>
<td>PATA</td>
<td>133MB/s</td>
</tr>
</tbody>
</table>
<p>SCSI（Small Computer System Interface）      </p>
<table>
<thead>
<tr>
<th>标准</th>
<th>速度</th>
</tr>
</thead>
<tbody>
<tr>
<td>Ultra Wide SCSI</td>
<td>40MB/s</td>
</tr>
<tr>
<td>Ultra2 Wide SCSI</td>
<td>80MB/s</td>
</tr>
<tr>
<td>Ultra160 SCSI</td>
<td>160MB/s</td>
</tr>
<tr>
<td>Ultra320 SCSI</td>
<td>320MB/s</td>
</tr>
</tbody>
</table>
<p>SATA（Serial Advanced Technology Attachment）       </p>
<table>
<thead>
<tr>
<th>标准</th>
<th>速度</th>
</tr>
</thead>
<tbody>
<tr>
<td>SATA 1.0</td>
<td>150MB/s</td>
</tr>
<tr>
<td>SATA 2.0</td>
<td>300MB/s</td>
</tr>
<tr>
<td>SATA 3.0</td>
<td>600MB/s</td>
</tr>
</tbody>
</table>
<p>SAS（Serial Attached SCSI）  <br />
传输的速率高达3Gb/s，以后会有6Gb/s乃至12Gb/s的高速接口出现。</p>
<p>M.2    </p>
<table>
<thead>
<tr>
<th>标准</th>
<th>速度</th>
</tr>
</thead>
<tbody>
<tr>
<td>Socket 2（B key-ngff）</td>
<td>700MB/s</td>
</tr>
<tr>
<td>Socket 3（M key-nvme）</td>
<td>4GB/s</td>
</tr>
</tbody>
</table></div>
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